In video conferencing, two people communicate audio-visually. Each person is near a video conferencing terminal having a camera and a display. The camera captures the image of the person, which is transmitted to the distant person. The image of the distant person, is displayed on the display. Each person in the video conference is looking at his or her display to view the image of the other person. The camera is usually placed somewhere near the display. Since the person is looking at the display, the image captured by the camera is of the person looking away from the camera at the display. Each person is, thus unable to maintain eye contact. Absence of eye contact during a conversation greatly reduces the effectiveness of communication.
Many prior art systems use a two-way mirror, also called a half silvered mirror or beam splitter. A two-way mirror simultaneously reflects some light and passes some light. FIG. 1 illustrates a prior art video conferencing system. A conferee 102 views the display 108 reflected in mirror 104 while the camera 106 captures images of the conferee 102. The image is captured from the same position that the conferee 102 is looking at. Teleprompters function this way.
Another prior art video conferencing system uses a terminal equipped with a beamsplitter for reflecting an image generated by a video display so that only the reflection and not a direct view of the display is seen by the conferee. The camera is positioned behind the viewing side of the beamsplitter to capture the conferee's image through the beamsplitter. The direct view of the display is blocked by an image blocking film applied between the beamsplitter and the display. Blocking the direct view of the video display greatly improves teleconferencing by eliminating the distraction of simultaneously viewing both the video display and the reflection of the display.
Prior art systems are quite bulky, especially when compared to modern display systems or modern teleconferencing systems. These systems waste a lot of energy, since a large amount of the energy radiated by the display is wasted since it goes through the two-way mirror.
Many prior art systems compute a three-dimensional model of the conferee. Then the model is used to render an image of the conferee as if a camera were placed just behind the screen. The three-dimensional model is computed from multiple views of the conferee captured by cameras near the display, or by illuminating the conferee using light of a particular known pattern, and using the data pertaining to the illumination caused by the light.
In another prior art system, the three-dimensional model is not computed, but the final virtual view from the direction of the display is estimated by visual flow interpolation techniques. All these methods are computationally expensive. Furthermore, they do not perfectly capture the required image, but just estimate it. Also, the closer the viewer is to the display, the larger the disparity between the images of the conferee captured by the various cameras, and the harder it is to compute an accurate three-dimensional model of the conferee. Also, such approximation models falter under improper lighting conditions and improper viewing conditions such as the presence of particulate matter or obstructions.
A prior art method for achieving eye-contact in a video conferencing situation uses a camera placed directly in the line of sight between the conferee and the display. Though a correct image of the user may be captured this way, the visual obstruction of the camera is not comfortable to the conferee.
An attachment mechanism removably secures the camera to a screen portion of a display screen such that the camera is disposed between the display screen and a person engaged in videoconferencing. The attachment mechanism can be a suction cup, strips of double-sided tape, or magnets. Magnetic force between the first and second magnets removably secures the camera to a screen portion of the flat panel display.
Other prior art systems use projection systems and are bulky in nature. Furthermore, these systems do not offer complete isolation of the camera sensor from the light due to the display, causing unwanted glare. Also, in many situations flat panel displays are preferred to projection systems due to image quality reasons.